298 BACTERtOLOQY. 



usually not be observed if it is trausplanted to ordi- 

 nary nutrient gelatin, agar-agar, bouillon, or potato ; 

 should it grow under these circumstances its develop- 

 ment will be very feeble. (Is this the case with com- 

 mon pus-producers ?) 



Sixth, it has no pathogenic properties for animals, 

 while several of the pyogenic cocci, notably staphylo- 

 eoeous aureus and streptoooccus pyogenes, are usually 

 capable of exciting pathological conditions. (This is 

 less commonly true of streptococcus pyogenes than of 

 staphylococcus aureus.) 



DIPLOCOCCUS INTEACELLULAEIS MENINGITIDIS. 



Of the several organisms mentioned that might be 

 mistaken for the gonococcus, no one of them is as sug- 

 gestive and none, per se, so important as that concerned 

 in the causation of epidemic cerebrospinal meningitis. 



This organism, described by Weichselbaum in 1887 

 under the name "diplococcus intracellularis meningi- 

 tidis," was found by him in the exudations of the brain and 

 spinal cord in six cases of acute cerebrospinal meningitis. 



As its name implies, it is a diplococcus, practically 

 always seen within the bodies of pus-cells (polymorpho- 

 nuclear leucocytes) in the exudations characteristic of 

 this disease. It is not seen within the other cells of the 

 morbid process. It stains readily with any of the ordi- 

 nary aniliue dyes, but is decolorized by the method of 

 Gram. It is conspicuous for the irregular way in which 

 it takes up the dye, some cells in a preparation (either 

 from the exudate or from cultures) being brightly and 

 intensely colored, others being much less so, or, indeed, 

 often nearly colorless. There is also a marked variation 

 in the size of individual cocci, some being normal, others 



